From the Guidelines
Elevated Mean Corpuscular Hemoglobin (MCH) is typically indicative of macrocytic anemia, which can be caused by vitamin B12 or folate deficiency, among other factors, as suggested by the study on cancer- and chemotherapy-induced anemia 1. When evaluating anemia, a morphologic approach characterizes it based on the mean corpuscular volume (MCV), with macrocytic anemia (> 100 fL) often being megaloblastic, indicating vitamin B12 or folate deficiency caused by insufficient uptake or inadequate absorption through lack of intrinsic factor 1. Some key points to consider in the evaluation of elevated MCH include:
- Vitamin B12 or folate deficiency as common causes of macrocytic anemia, which can lead to elevated MCH
- Other potential causes such as alcoholism, liver disease, certain medications (e.g., anticonvulsants, chemotherapy drugs, immunosuppressants), and genetic conditions (e.g., hereditary spherocytosis)
- The importance of additional tests, such as complete blood count, peripheral blood smear, vitamin B12 and folate levels, liver function tests, and possibly bone marrow examination, to determine the underlying cause of high MCH, as these tests can help identify the specific cause of macrocytic anemia and guide appropriate treatment 1. It is essential to identify and address the underlying cause of elevated MCH to improve patient outcomes and quality of life.
From the FDA Drug Label
- 9 Macrocytosis Hydroxyurea capsules may cause macrocytosis, which is self-limiting, and is often seen early in the course of treatment.
The macrocytosis caused by hydroxyurea capsules may lead to an increase in Mean Corpuscular Hemoglobin (MCH), as macrocytosis is a condition characterized by larger than normal red blood cells, which can result in an increase in the average amount of hemoglobin per red blood cell.
- Key points:
- Hydroxyurea capsules may cause macrocytosis
- Macrocytosis can lead to an increase in MCH
- This effect is self-limiting and often seen early in the course of treatment 2
From the Research
Causes of Elevated Mean Corpuscular Hemoglobin (MCH)
- Elevated MCH can be caused by various factors, including macrocytic anemias 3
- Macrocytic anemias are generally classified into megaloblastic or nonmegaloblastic anemia, with megaloblastic anemia caused by deficiency or impaired utilization of vitamin B12 and/or folate 3
- Nonmegaloblastic macrocytic anemia can be caused by diseases such as myelodysplastic syndrome (MDS), liver dysfunction, alcoholism, hypothyroidism, and certain drugs 3
- Combined deficiencies of iron and vitamin B12 can also lead to elevated MCH, with a study finding that patients with combined iron and vitamin B12 deficiency had decreased MCH levels compared to those with pure iron deficiency anemia 4
- However, another study found that higher MCH was associated with increased major adverse cardiovascular events (MACEs) in nonanemic patients with acute coronary syndrome 5
Laboratory Measurements and MCH
- Spurious increased MCHC can be caused by analytical errors, such as RBC agglutination or optical interference 6
- The use of new parameters such as RBC-O and HGB-O can help correct abnormalities and deliver appropriate results 6
- Reticulocyte parameters can also be used to detect RBC disease patients with elevated MCHC 6
Relationship between MCH and Other Health Conditions
- A study found that low serum vitamin B12 levels were associated with the severity of some psychosis symptoms, including hallucinations and negative symptoms 7
- However, another study found that MCH showed no predictive value for MACEs and no correlation was found between MCH and homocysteine levels in ACS patients with anemia 5